Shock absorbing attachment for fork lift trucks



P. O. MILLER March 5, 1963 SHOCK ABSORBING ATTACHMENT FOR FORK LIFT TRUCKS Filed July 20, 1961 INVENTOR Pau/ 0 Mi/ler FIG. 4

Unite a, sea Patented Mar. 5, 1963 3,939,680 SHOCK AESGRBTNG ATTACHMENT FGR FQRK LET TRUCKS Paul 0. Miller, 3515 Merrie, flireyenne, Wye. Filed July 29, 1961, Ser. No. 125,421 2 Claims. (Cl. 214-754?) This invention relates broadly to industrial trucks of the fork lift type and more particularly to shock absorbing means mountable upon the lifting forks to prevent damage to the load carrying pallets and skids customarily handled by these trucks.

Industrial fork lift trucks are widely used to lift and transport loads which are stacked on pallets and skids generally made of wood. The lifting forks of the truck pass between the top and bottom walls of the wooden pallet or beneath the top wall of the skid and the lifting forks are then elevated with the pallet or skid and the load upon it, so that the load may be transported. Frequently, the forks enter the pallet or skid with considerable speed and the rear upstanding portions of the lifting forks may strike the endmost board of the pallet or skid with considerable force, thereby splitting, chipping or otherwise damaging it and sometimes causing the pallet board to become un-nailed or separated from the main side rails of the pallet.

According to the present invention, means in the nature of a shock absorbing attachment is applied to the vertical portion of each lifting fork of the fork lift truck to cushion the impact of the forks with pallets and skids, thereby preventin injury to the latter and thus effecting a large saving of money in large industrial installations. It is therefore a prime object of the invention to provide means of the mentioned character which will greatly prolong the useful life of pallets and skids made of wood or other material.

A further object is to provide a shock absorber or bumper of the mentioned character the nature of a removable attachment for the lifting forks of substantially any standard fork lift truck requiring little or no alteration in the structure of the lifting fork and not interfering in the slightest with the normal operation or utility of the industrial truck.

Another object is to provide a device of the character mentioned which is economical to manufacture, sturdy and durable, and very easy to install upon a fork lift truck.

Other objects and advanta es of the invention will be apparent during the course of the following detailed description.

In the accompmiying drawings forming a part of this application and in which like numerals are employed to gnate like parts throughout the same,

FIGURE 1 is a perspective View of a shock absorbing attachment for fork lift trucks according to the invention,

FIGURE 2 is a central vertical section taken on line 22 of FlGURE 1,

FIGURE 3 is a perspective view of the invention applied to the lifting forks of the truck,

FEGURE 4 is a fragmentary side elevation partly in section of the shock absorbing attachment and showing its relation during use to the lifting fork and load carrying pallet.

in the drawings wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral 1% designates generally a conventional industrial or fork lift truck which may be any one of a number of well'known standard makes, and to which the present invention is applicable. The fork lift truck It has the usual upright forward mast 11 and vertically movable carriage 12, under influence of lifting means 13, all conventional in construction. A pair of lifting forks 14 having rear vertical portions 15 are carried adjustably by the carriage 12 and adapted to be raised and lowered therewith and to have their lateral spacing changed to meet the needs of a particular load carrying assignment. The construction and operation of the truck 10 is conventional and well known to those skilled in the art and need not be described in further detail herein. The invention may be applied to substantially any conventional fork lift truck, and the model shown is for the purpose of illustration only and should not be construed in any limiting sense.

According to the invention, a pair of generally rectangular, relatively thick shock absorbing pads 16 or bumper elements are mounted on the forward faces of the vertical portions 15 of lifting forks 14 as shown in the drawings. The pads 16 are formed of rubber, synthetic rubber, camelback or other rubberlike material, and the pads have resiliency characteristics approximating those of the ordinary automobile tire casing rubber or the like.

Each pad or bumper element 16 is of a width approximating that of the vertical fork portion 15 and of a height or length to span about one-half of the vertical length of fork portion 15 as shown in FIGURE 3.

Each resilient pad 16 is formed by molding or the like and is preferably vertically ribbed or grooved in its forward face as indicated at 17 in the drawings. This materially increases the resiliency of the pad 16 without materially changing its wearability or necessitating the use of softer rubber to achieve the desired cushioning effect.

Embedded within each pad 16 centrally is a reinforcing metal strip or plate 13 having a pair of intermediate openings 1? which receive the material of the pad during the m ding process to firmly anchor the plate 13 therein. Near the upper and lower ends of the plate 18 and pad, the former a pair of studs 24 and 21 rigdily anchored by welding or the like within openings 22 formed in the plate 13 for this purpose. The studs 29 and 21, rigid with the plate 18, are molded in the resilient pad 16, as shown, and project beyond the rear face thereof and at right angles thereto, FIGURE 2. The lower stud 21 is screw-threaded at 23 for the reception of a nut 24. The upper stud 269 is smooth or unthreaded and may be somewhat shorter than the lower stud and serves merely as a dowel or pilot during use as will be described. if preferred, however, the upper stud 29 may be identical to the lower stud 21 and screw-threaded.

The pads 16 are secured to the front faces of the upright fork portions 15, as shown in the drawings, and the pads are readily removable when desired. The fork portion 15 which may be channel-shaped in cross section is provided in its front wall with a pair of openings to receive the studs 2t? and 21 as best shown in FIGURE 4. The nut 24 serves to secure the pad 16 in assembled relation with the litfing fork portion 15, and the upper stud 2i) has piloting engagement with the upper opening of the fork to hold the pad against lateral movement. The rear corners 25 and 26 of each pad are preferably rounded to lit the contours of the lifting fork where the horizontal portion thereof joins the vertical portion 15. The pads re may be secured to the fork portions 15 in any other preferred manner and the present arrangement utilizing the studs 28 and 21 is illustrative only and should not be construed in a limiting sense. On some makes of trucks, where the fork portions 15 are not channel-shaped and there may not be clearance for the nut 24 at the rear side of the fork, the studs may be flush with the rear face of the vertical fork portion and secured thereto by welding or the like. Various means may be employed for securing the shock absorbing pads to the forks detachably or permanently within the scope of the invention. The lower ends of the pads 16 may rest substantially upon the horizontal fork portions as shown in the drawings.

In use, the fork lift truck is operated to lift and transport palletized loads and loads mounted upon skids. The pallets and skids are generally made of wood and assembled by nailing and while quite sturdy and durable, they can be damaged by severe impact and have their useful life shortened.

With reference to FIGURE 4, a load L to be lifted and transported by the truck 10 is shown mounted on a wooden pallet P having top and bottom boards 27 and 28 arranged in the usual manner above and below the side rails, to provide a horizontal passage 29 to receive the horizontal portions or tines of the forks 14.

When the forks 14 enter the pallet passage 29, there is atendency for the upright fork portions 15 to strike the rearmost upper board 27 with considerable force and thereby loosen, split, chip or otherwise damage the same as previously explained, and the prime purpose of the shock absorbing elements or pads'16 is to protect the pallet in this respect and to absorb the shock upon the top board 27' at thecmoment of engagement of the lifting forks with the pallet andrload. The provision of the pads 16 not only protects the pallet and therefore prolongs its useful life and saves money. directly, but also allows the operator of the truck to approach the load freely and without the extreme caution that is necessary where the pads 16 are not used, thereby rendering the complete operation of the truck more eflicient and speedy and saving further money in the overall operation. a

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in theshape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or the scope of the subjoined claims. c

Having thus described my invention, I claim:

1. In a fork lift truck, a pallet lifting fork having a horizontal arm to enter the pallet and a vertical arm adapted to engage the lead board of the pallet and likely to impart an abrupt shock force to said lead board damaging it, a resilient rubber-like shock absorbing pad of substantially the same width as the vertical arm of said fork and mounted directly upon the forward face of said vertical arm and covering the same from a point adjacent the horizontal fork arm to a point generally midway up the vertical arm, a substantially rigid anchor plate embedded bodily within said rubber-like pad and entirely enclosed by the pad with portions of the pad having substantial thickness arranged on opposite sides of and around the margin of the anchor plate, a pair of spaced studs rigidly securedto the anchor plate within said pad and extending substantially at right angles thereto and projecting outwardly of the rear faceof the pad during use there f, at least one or said studs being screwthreaded, said vertical arm of said fork having a pair of vertically spaced openings formed therethrough receiving said studs, and a nut engaging said threaded stud and bearing upon the rear face of said vertical arm to releasably secure the pad to the vertical arm.

2. The invention as defined by claim 1, and wherein the front face of said pad is alternately grooved and ribbed vertically to provide a tread face thereon of increased resiliency compared to the remainder of the body of said pad, said anchor plate provided with spaced openings intermediate said studs to receive the material of the pad during molding thereof for unitizing the anchor plate and pad.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A FORK LIFT TRUCK, A PALLET LIFTING FORK HAVING A HORIZONTAL ARM TO ENTER THE PALLET AND A VERTICAL ARM ADAPTED TO ENGAGE THE LEAD BOARD OF THE PALLET AND LIKELY TO IMPART AN ABRUPT SHOCK FORCE TO SAID LEAD BOARD DAMAGING IT, A RESILIENT RUBBER-LIKE SHOCK ABSORBING PAD OF SUBSTANTIALLY THE SAME WIDTH AS THE VERTICAL ARM OF SAID FORK AND MOUNTED DIRECTLY UPON THE FORWARD FACE OF SAID VERTICAL ARM AND COVERING THE SAME FROM A POINT ADJACENT THE HORIZONTAL FORK ARM TO A POINT GENERALLY MIDWAY UP THE VERTICAL ARM, A SUBSTANTIALLY RIGID ANCHOR PLATE EMBEDDED BODILY WITHIN SAID RUBBER-LIKE PAD AND ENTIRELY ENCLOSED BY THE PAD WITH PORTIONS OF THE PAD HAVING SUBSTANTIAL THICKNESS ARRANGED ON OPPOSITE SIDES OF AND AROUND THE MARGIN OF THE ANCHOR PLATE, A PAIR OF SPACED STUDS RIGIDLY SECURED TO THE ANCHOR PLATE WITHIN SAID PAD AND EXTENDING SUBSTANTIALLY AT RIGHT ANGLES THERETO AND PROJECTING OUTWARDLY OF THE REAR FACE OF THE PAD DURING USE THEREOF, AT LEAST ONE OF SAID STUDS BEING SCREWTHREADED, SAID VERTICAL ARM OF SAID FORK HAVING A PAIR OF VERTICALLY SPACED OPENINGS FORMED THERETHROUGH RECEIVING SAID STUDS, AND A NUT ENGAGING SAID THREADED STUD AND BEARING UPON THE REAR FACE OF SAID VERTICAL ARM TO RELEASABLY SECURE THE PAD TO THE VERTICAL ARM. 